With the advent of various portable devices, it is not rare for a person to own multiple portable devices. Many portable devices have the communication function to update information in real time.
For example, a user may carry multiple cellular communication-enabled devices such as mobile phone, electronic book (ebook), multimedia player, and tablet Personal Computer (PC). For another example, a vehicle may be equipped with various process modules supporting cellular communication on the move. The process modules may include a cellular communication-enabled black box, a cellular communication-enabled navigator, and a cellular communication-based emergency call device.
In such a case that a user owns multiple portable devices, it is likely for the user (including transport means such as vehicle) to use the portable devices for communication simultaneously. At this time, the mobility levels measured by the portable devices carried by a single user are identical among each other. However, if the communication service is provided based on the mobility levels measured by the respective devices without consideration of the equal mobility of the devices, this may cause problem.